This application claims priority of Korean patent Application No. 2000-74760 filed in the Korean Industrial Property Office on Dec. 8, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a color selection apparatus for a cathode ray tube, and more particularly, to a color selection apparatus capable of reducing the weight of a frame by improving the structure of a pair of elastic members.
A cathode ray tube (CRT) is a device for displaying images on a screen by emitting three electron beams from an electron gun and landing the electron beams onto a phosphor screen. The electron beams are divided onto corresponding red R, green G, and blue B phosphor layers respectively through a color selection apparatus, which is mounted in front of the phosphor screen.
FIG. 1 is a perspective view of a prior art color selection apparatus. The color section apparatus 1 includes a mask 3 formed with a plurality of slits 3a for passing electron beams, and a frame 5 supporting the mask 3, wherein the frame 5 is formed with a pair of supporting members 7 fixing the mask 3, and a pair of elastic members 9 connecting the supporting members 7.
Generally, the mask 3 is tensed in a minor axial direction (y-axis direction in the drawing), and the long sides of the mask 3 are fixed to the supporting members 7 by a well-known spot welding method. During the assembly of the color selection apparatus 1, the elastic members 9 are deformed elastically by the tension toward the center of the mask 3, so that the force of restitution of the elastic members 9 supports the tension of the mask 3.
FIG. 2 is a sectional view taken along line Ixe2x80x94I of FIG. 1. The elastic members 9 are formed as a hollow pipe having a square cross section as shown in FIG. 2.
In connection with the function of the frame that is supporting the tension of the mask, U.S. Pat. Nos. 4,725,756 and 5,644,192 disclose various structures of the color selection apparatus to improve the strength of the frame. However, the prior art provides either an additional member attached to the frame, or more heavy elastic members, for supporting the increasing tension applied to the mask.
Accordingly, the structure and manufacturing process of the color selection apparatus becomes complicated. Moreover, the color selection apparatus becomes enlarged as the screen is enlarged, thereby increasing the weight of the color selection apparatus.
Such an increase of the weight of the color selection apparatus makes it difficult to attach the color selection apparatus onto a face panel and to detach the color selection apparatus from the face panel when manufacturing the phosphor screen. As a result, the manufacturing yield of the phosphor screen is reduced.
Also, in elastic members 9 having a square cross section as described above, the gas generated when welding the elastic members 9 and the supporting members 7 remains within the elastic members 9. This is disadvantageous because the manufacturing process of the color selection apparatus becomes complicated. For example, a hole should be formed on the elastic members 9 to remove the residual gas.
It is an object of the present invention to provide a color selection apparatus for a cathode ray tube in which the weight of a frame may be effectively reduced.
It is another object of the present invention to provide a color selection apparatus for a cathode ray tube capable of preventing gas generated when welding the elastic members and the supporting members from remaining within the elastic members.
In order to achieve the above objects of the present invention, a color selection apparatus includes a frame formed with a pair of supporting members arranged facing each other with a predetermined distance therebetween, a pair of elastic members coupled to the supporting members, and a mask formed with a plurality of slits for passing electron beams and fixed at the supporting members under tension. Each of the elastic members is formed with a pair of opposite parts facing each other in parallel at a predetermined distance therebetween and a connection part is perpendicularly arranged between the opposite parts.
Preferably, the elastic member is formed with a pair of opposite parts facing each other in a direction where the electron beams advance, and the connection part is perpendicularly arranged between the opposite parts.
Alternatively, the elastic member is formed with a pair of opposite parts facing each other in a major direction of the mask, and the connection part is perpendicularly arranged between the opposite parts.
Preferably, the elastic member is formed to maintain a secondary moment of inertia M2 at a level higher than 85% of M1, wherein M1 is a secondary moment of inertia of an elastic member which is formed is a hollow pipe having a square cross section and designed under the same tension.